The purpose of the Virus and Cell Biology Core [VCBC] is to support Projects 1-4 in the proposed Program Project Grant [PPG]. The VCBC will participate in the following investigations proposed in this PPG: (1). The identification of mechanisms of action of actors from the urine of pregnant women that exhibit anti-KS activity; (2). The isolation and characterization of factors from the urine of pregnant women that exhibit anti-KS activity; (3) The relationship between Kaposi's sarcoma (KS) and the human herpesvirus HHV8 as a potential etiologic factor; (4). And the molecular determinants of KS cell lines. The VCBC has been actively involved in developing in vitro assays and cellular models for AIDS and has experience working with in vitro assays designed to study various aspects of KS. The VCBC is to provide centralized services and biological samples for Projects 1-4 in the PPG and to assure consistent quality and uniformity of reagents and assays. The VCBC goals, which are incorporated into six Specific Aims, are: to receive and monitor the inventory levels of all biological material in the PPG and to maintain all biological materials at optimal storage conditions; to provide reagents [viruses, cells, monoclonal antibodies, and synthetic peptides] to individual investigators and to perform bioassays to further the Specific Aims of the investigations proposed in the individual projects; to collate data with the Animal Core Facility [Core B] for reporting back to Projects 1-4. Maintaining materials, providing virus stocks and cells, and performing and/or coordinating bioassays through the VCBC will ensure that the biological assays for all the projects of this PPG are conducted with screened, standardized reagents, thus facilitating comparisons among the data sets generated by all the projects.